The present invention relates to a new and distinct cultivar of Agastache, given the name, ‘TNAGAPDB’. Agastache is in the family Lamiaceae. This new cultivar is one of several selections of new Agastache using hardy and dwarf Agastache species in the breeding lines to provide hardiness and compactness. The new cultivar is a selection from the open pollinated seedlings of Agastache 66-04. The new cultivar was selected for its compact habit, hardiness, and dark blue flowers.
Compared to the seed parent, Agastache 66-04 the new cultivar is shorter.
Compared Agastache ‘Violet Vision’ (U.S. Plant Pat. No. 25,274), the new cultivar has darker blue flowers and is shorter and more compact.
Compared Agastache ‘Kudos Silver Blue’ (U.S. Plant Pat. No. 25,344), the new cultivar has purple blue flowers rather than silver blue and is shorter and more compact.
This plant exhibits the following characteristics that make it unique:                1. purple blue flowers in large inflorescences,        2. a long bloom time,        3. a very short, compact habit, and        4. excellent vigor.        
The new variety has been reproduced only by asexual propagation (stem cuttings and micropropagation using apical buds and nodes). Each of the progeny exhibits identical characteristics to the original plant. Asexual propagation by stem cuttings and micropropagation using apical buds and nodes as done in Canby, Oreg., shows that the foregoing characteristics and distinctions come true to form and are established and transmitted through succeeding propagations. The present invention has not been evaluated under all possible environmental conditions. The phenotype may vary with variations in environment without a change in the genotype of the plant.